PERCHLORIC ACID FUME HOODS
LABORATORY DESIGN BASICS
Perchloric acid is a chemical subject to violent explosions. Perchloric acid fume hoods, and their exhaust systems, are designed to allow safe use of this chemical by meeting five criteria.
PERCHLORIC ACID FUME HOOD DESIGN
They are made of materials that don’t react to percholoric acid. Type 316 stainless steel and rigid PVC are materials safe to use in percholoric fume hood construction. Stainless steel is extremely safe, though its surface will wear after repeated exposure to acid. Rigid PVC will last longer than stainless, but because manufacturers tend to specialize in plastics and not in fume hood construction, quality can be compromised.
They are watertight. Perchloric acid fume hoods must allow proper water wash down, and the system must be designed so there is complete coverage of the area behind the back baffle, without getting water on the baffle system or on the working surface of the hood. The ducting requires a wash down system that results in comprehensive coverage of all ducting components. A trough along the back of the work surface must be big enough to accommodate water volume.
An exhaust collar that extends ¼-inch inside the hood chamber and is seam welded to the inside surface of the chamber will ensure that water flows directly into the hood, and not across the hood work area.